JPH04125432U - Capacitor type instrument transformer - Google Patents

Abstract

(57) [Summary] [Purpose] To detect insulation deterioration of capacitors in capacitor-type potential transformers at an early stage. [Structure] A capacitor current detector 7 for detecting a current flowing through a voltage dividing capacitor and a burden current detector 8 for detecting a burden current are provided. A correction current component calculation means 10 is provided which receives the outputs of both detectors as input and calculates a charging current component that is not affected by the burden current as a correction current component. The corrected current component and the current detected value by the capacitor current detector 7 are given to charging current component calculating means to calculate a charging current component that is not affected by the load. The alarm signal generating means 12 generates an alarm signal when the charging current component exceeds a set value.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a capacitor-type potential transformer.

0002

[Conventional technology]

As shown in Figure 3, a capacitor-type voltage transformer has a main capacitor 1 and a main voltage transformer. a capacitor coupling section consisting of a voltage dividing capacitor 2 connected in series to the capacitor; Insert into the transformer 3 that inputs the voltage across the voltage dividing capacitor and the primary circuit of the transformer. A resonant reactor 4 is provided. Main capacitor 1 and voltage dividing capacitor 2 The voltage of the power supply 5 is applied to both ends of the series circuit, and the voltage of a voltmeter etc. is applied to the secondary side of the transformer 3. (Impedance Zb) 5 is connected.

0003 In capacitor-type potential transformers, the capacitor coupling part provides the main insulation; Insulation deterioration at the capacitor joint can lead to serious accidents. Poor insulation of capacitor coupling part The phenomenon begins with an increase in tanδ due to deterioration of the dielectric, and if left untreated, it will eventually Progresses from partial dielectric breakdown to complete dielectric breakdown.

0004 As tanδ increases, the active component in the charging current increases. Also partial insulation When destruction occurs, the number of capacitors connected in series decreases, resulting in an increase in capacitance. The absolute value of the charging current itself increases.

[0005] Therefore, by detecting the charging current of the capacitor and comparing it with the normal value, , insulation deterioration of the capacitor coupling part can be monitored. Traditionally, partial pressure capacitors A current detector (current transformer) 7 is provided to detect the current I2 flowing through the transformer 2. The output of the output device 7 is input to the monitoring device 9', and the current I2 flowing through the voltage dividing capacitor 2 is detected. The insulation deterioration of the capacitor coupling part was monitored based on the output value.

[0006]

[Problem that the idea aims to solve] In Figure 3, the capacitance of main capacitor 1 and voltage dividing capacitor 2 is C 1 and C2, the inductance of the resonant reactor 4 is L, and the power supply voltage is E (vector Quantity), the current flowing through voltage dividing capacitor 2 is converted to I2 (vector quantity), the primary side. If the impedance of burden 6 is Zb ′ (vector quantity) and the angular frequency of the power source is ω, then , the current I2 flowing through the voltage dividing capacitor 2 is given by the following equation (1).

[0007] I2 = Ic - Io...(1) Here, Ic is the current determined only by the capacitance of the capacitor without being affected by the load. component, which is given by the following equation (2).

[0008] Ic = jω{C1 ・C2 /(C1 +C2)}E …(2) In addition, Io is a current component that changes depending on the impedance Zb of burden 6, and the following (3) Determined by the formula.

[0009] Io = {ωC1 ・C2 / (C1 + C2)}E (ωL / Zb) ... (3) In this way, the current flowing through the voltage dividing capacitor 2 includes a component that is affected by the load. Therefore, even if this current is monitored, it is difficult to determine whether the change is due to deterioration of the capacitor insulation. , it is not possible to determine whether this is due to a change in the impedance of the load, and the capacitor connection It was not possible to accurately monitor insulation deterioration at joints.

0010 The purpose of this invention is to accurately monitor insulation deterioration of capacitor coupling parts. An object of the present invention is to provide a capacitor type potential transformer.

[0011]

[Means to solve the problem]

The present invention consists of a main capacitor and a voltage dividing capacitor connected in series with the main capacitor. A transformer whose input is the voltage across the voltage dividing capacitor, and a primary circuit of the transformer. The capacitor is isolated from the inserted resonant reactor and the current flowing through the voltage dividing capacitor. In capacitor-type potential transformers equipped with a monitoring device for monitoring edge deterioration, This allows the insulation deterioration of the capacitor to be accurately monitored.

0012 Therefore, in this invention, a capacitor is used to detect the current flowing through the voltage dividing capacitor. and a burden current detector that detects the burden current flowing to the secondary side of the transformer. The monitoring device connects the output of the capacitor current detector, the output of the burden current detector, and the circuit. Compensate the current component flowing through the voltage dividing capacitor due to the influence of the burden current from the circuit constant. A correction current component calculation means that calculates it as a positive current component and a capacitor current detector are used to calculate the current component. A charging current component that is not affected by the burden current is determined from the detected current and the correction current component. A charging current component calculation means that calculates the charging current component, and a controller that calculates the charging current component when it exceeds the set value and alarm signal generating means for generating an alarm signal indicating deterioration of the capacitor.

[0013]

[Effect]

With the above configuration, the charging current component detection means is a pure battery that is not affected by the load. Detects the best capacitor charging current. The alarm signal generation means uses this detection means. The detected charging current is monitored and the capacitor is activated when the charging current exceeds the set value. The insulation deterioration of the capacitor coupling part can be accurately monitored to generate an alarm signal indicating the deterioration of the capacitor. can be viewed.

[0014]

【Example】

Figure 1 shows an embodiment of the present invention, in which 1 and 2 are the main components, respectively. 3 is a transformer, and 4 is a resonant reactor. Main controller Capacitor 1 and voltage dividing capacitor 2 constitute a capacitor coupling section, and this capacitor The output voltage E (vector quantity) of the power source 5 is applied to the sensor coupling portion. Also a transformer A load 6 is connected to the secondary side of 3.

[0015] A current detector 7 consisting of a current transformer is attached to the circuit connected to the voltage dividing capacitor 2. , a current detector 8 also consisting of a current transformer is attached to the circuit connected to the load 6. Ru. The outputs of current detectors 7 and 8 are input to a monitoring device 9.

[0016] As shown in FIG. 2, the monitoring device 9 includes a correction current component calculation means 10 and a charging current It is composed of a component calculation means 11 and an alarm signal generation means 12.

[0017] The correction current component calculation means 10 detects the output of the capacitor current detector 7 and the burden current. From the output of circuit 8 and the circuit constants, it is determined that the voltage flowing through the voltage dividing capacitor is affected by the burden current. The current component is calculated as the corrected current component Io.

[0018] The charging current component calculating means 11 calculates the current I detected by the capacitor current detector. 2 and the corrected current component Io, calculate the charging current component Ic that is not affected by the burden current. Calculate.

[0019] The alarm signal generating means 12 activates the capacitor when the charging current component Ic exceeds a set value. generates an alarm signal indicating deterioration of the sensor.

[0020] Io in the above formula (3) can be expressed as follows.

Io = {ωC1 ・C2 / (C1 + C2)} E (ωL / Zb ′) = {C1 E / (C1 + C2 )} (1 / Zb ′) ω ² C2 L = Ib ω ² C2 L … ( 4) Here, Ib is the burden current measured on the primary side of the transformer, and Io, Ib, E, and Zb' are all vector quantities. If the burden current measured by the current detector 8 on the secondary side of the transformer is ib, and the turns ratio of the transformer is n, then Ib = (1/n)ib...(5) Expressing (5) into equation (4) By substituting, Io = (ib /n)ω ² C2 L (6) In equation (6), since the circuit constants ω, C2, L and n are known, by measuring the burden current i b The component Io affected by the current can be calculated.

[0022] From equation (1), the current component Io affected by the load is taken as the corrected current component, and the current This correction current component Io (vector quantity) is added to the current I2 (vector quantity) detected by the detector 7. By adding a It can be seen that the capacitor charging current component Ic can be calculated.

[0023] The alarm signal generating means 12 generates a preset absolute value of the charging current component and an effective current component. , and the calculated absolute value of the charging current component Ic and the effective current component. Outputs an alarm signal when the calculated value exceeds the set value. Lamp with this alarm signal etc., to notify that the insulation of the capacitor has deteriorated.

[0024] Each means of the monitoring device 9 can be realized by a microcomputer. Ru.

[0025]

[Effect of the idea]

As described above, according to the present invention, the capacitor can be used without being affected by the load. Since charging current can be monitored, deterioration of capacitor insulation can be detected at an early stage. There are advantages that can be obtained.

[0026] As insulation deterioration of the capacitor progresses, in the worst case, the capacitor may explode. Therefore, if insulation deterioration of capacitors is left untreated, it can cause serious damage to human life and equipment. Not only is there a possibility that the There is. Therefore, this invention makes it possible to detect insulation deterioration of capacitors at an early stage. The effects are of great significance from the perspective of predictive maintenance.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a monitoring device used in an embodiment of the present invention.

FIG. 3 is a configuration diagram showing the configuration of a conventional capacitor type potential transformer.

[Explanation of symbols]

1... Main capacitor, 2... Voltage dividing capacitor, 3... Transformer,
4... Resonant reactor, 7... Capacitor current detector, 8...
Burden current detector, 9... Monitoring device, 10... Correction current component calculating means, 11... Charging current component calculating means, 12... Alarm signal generating means.

Claims (1)

[Scope of utility model registration request] Claim 1: A main capacitor, a voltage dividing capacitor connected in series with the main capacitor, a transformer receiving the voltage across the voltage dividing capacitor as input, and a voltage dividing capacitor connected in series with the main capacitor, a transformer having a voltage across the voltage dividing capacitor as input, and a voltage dividing capacitor connected in series with the main capacitor, a transformer having a voltage across the voltage dividing capacitor as input, and a voltage dividing capacitor connected in series with the main capacitor. A capacitor-type potential transformer comprising a resonant reactor and a monitoring device for monitoring insulation deterioration of the capacitor based on the current flowing through the voltage dividing capacitor, a capacitor current detector detecting the current flowing through the voltage dividing capacitor; and a burden current detector that detects a burden current flowing in the secondary side of the transformer, and the monitoring device detects the influence of the burden current from the output of the capacitor current detector, the output of the burden current detector, and circuit constants. corrective current component calculation means for calculating a current component flowing through a voltage dividing capacitor as a corrected current component based on the current detected by the capacitor current detector; A capacitor comprising a charging current component calculating means for calculating a charging current component, and an alarm signal generating means for generating an alarm signal indicating deterioration of the capacitor when the charging current component exceeds a set value. type instrument transformer.